1. Field of the Invention
This invention relates to friction-reducing lubricating oil compositions which provide improved fuel economy and oxidation inhibition in internal combustion engines. More particularly, this invention relates to finished lubricating oil compositions that contain both a fuel economy additive system and an antioxidant component. The fuel economy system comprises: (1) a member selected from the group consisting of mono and higher esters of polyols, primary amines, primary ether amines, ether diamines, polyethoxylated amines and polyethoxylated diamines, ethoxylated ether amines, the said amines and diamines containing alkyl and alkylene groups of from 2 to about 30 carbon atoms, aliphatic amides and polyethoxylated amides containing alkyl and alkylene groups of up to about 30 carbon atoms; and (2) a compound containing a Group IA metal of the Periodic Table wherein the Group IA metal is present in the finished lubricating oil in an amount of from about 10 ppm (wt) to less than about 1000 ppm (wt). The antioxidant component comprises a transition element metal compound that is soluble or at least dispersible in hydrocarbons, wherein the metal is a transition metal of an atomic number of from 21 to 47 of the Periodic Table of Elements.
2. Description of the Prior Art
Since the automobile fuel shortage of the 1970's, emphasis has been placed on the conversion of energy and fuels. The government of the United States of America has enacted Federal Regulations which define gasoline-mileage requirements which must be met by the automobile manufactures in that the new automobiles must provide a specified minimum gasoline mileage. The newer automobiles are smaller in size and lighter in weight, as a result of these regulations.
Another way to conserve fuel is to use friction-reducing additive materials in the lubricating oils employed in crankcases of internal combustion engines. A reduction in friction in the engine results in a decrease in the amount of fuel consumed by that engine.
It is known that various lubricating oil additives are capable of reducing the amount of fuel that is consumed by an internal combustion engine. For example, in United Kingdom Patent Application GB 2,097,813A, it was disclosed that certain esters provide reduced fuel consumption. In U.S. Pat. No. 4,208,293, Zaweski disclosed that a fatty acid amide of diethanolamine, or a fatty acid ester of diethanolamine, or a mixture thereof, or esteramides formed therefrom can be used as additives in a lubricating oil composition to reduce friction in an internal combustion engine. In U.S. Pat. No. 4,201,684, Malec taught that a sulfurized fatty acid ester, a sulfurized fatty acid amide, or a sulfurized fatty acid esteramide of an alkoxylated amine, such as ethanolamine, can be used also as a friction modifier in a lubricating oil composition. In U.S. Pat. No. 4,383,931, Ryu et al. disclosed that an oil-soluble molybdenyl bis-b-diketonate is capable of providing antifriction properties to a lubricating oil composition when used in combination with an oil-soluble active sulfur donor, such as zinc dialkyldithiophosphate,
In U.S. Pat. No. 4,326,972 and its British equivalent, United Kingdom Patent Application GB 2,023,169A, Chamberlin III disclosed certain lubricating oil compositions and a method for reducing fuel consumption in an internal combustion engine. He stated that fuel economy is attained by employing a lubrication oil composition comprising: (1) an oil of lubrication viscosity; (2) a sulfurized mixture comprising at least one ester of a substantially aliphatic carboxylic acid containing from about 8 to about 30 carbon atoms and a substantially aliphatic alcohol, at least one substantially aliphatic carboxylic acid containing from about 8 to about 30 carbon atoms, and at least one substantially aliphatic monoolefin containing from about 8 to about 36 carbon atoms; and (3) at least one oil-dispersible basic alkali metal sulfonate. He disclosed that such a lubricating oil composition, when used as a crankcase oil in an internal combustion engine, improves the operation of that engine by decreasing fuel consumption.
European Patent Application No. 83302155.3 (European Publication No. 092946) taught that a partial ester of a fatty carboxylic acid containing from 16 to 18 carbon atoms and glycerol and an oil-soluble organic copper compound, when present in a lubricating oil composition, act together to reduce friction in the crankcase of an internal combustion engine utilizing said composition.
In U.S. Pat. No. 4,280,916, Richards et al., disclose a motor oil composition which contains an oil of lubricating viscosity, an ashless dispersant, such as a polyisobutenyl succinate, an oil-soluble detergent sulfonate, salicylate, and/or phenate, and at least one C.sub.8 -C.sub.24 aliphatic monocarboxylic acid amide, the latter being present in an amount that is sufficient to reduce fuel consumption of an internal combustion engine that is employing the motor oil composition as the crankcase lubricating oil of that engine.
Now there has been found unexpectedly a lubricating oil composition that not only reduces fuel consumption, but also provides outstanding stability to oxidative degradation.